Thai authorities have made travel by public transport in Bangkok free for a week, the latest tactic to try to tackle soaring levels of air pollution that have already seen hundreds of schools closed and employees working from home. The travel concession, launched Saturday, allows passengers to ride buses and elevated and underground electric trains in the capital without charge. Authorities hope the move will cut the number of private cars on the road, to reduce one key factor driving the surge in pollution. Air pollution has been a problem for many years in Thailand’s north, but in recent years Bangkok has also begun to suffer as well.